Slot antenna which is fed at two points



Oct. 31, 1961 R. A. DAVIS 3,007,164

SLOT ANTENNA WHICH IS FED AT TWO POINTS Filed April 22, 1955 3SheetsSheet 1 iiili 3 37 F |G.6 1 R088 A. DAVIS IN VEN TOR.

HIS ATTORNEY R. A. DAVIS SLOT ANTENNA WHICH IS FED AT TWO POINTS Oct.31, 1961 3 Sheets-Sheet 2 Filed April 22, 1955 FIG-7- l-llllll LlllllllE V m A S S O R IN V EN TOR.

HIS ATTORNEY 3 Sheets-Sheet 5 HIS ATTORNEY Oct. 31, 1961 R. A. DAVISSLOT ANTENNA WHICH IS FED AT TWO POINTS United States Patent 3,007,164SLOT ANTENNA WHICH IS FED AT TWO POINTS Ross A. Davis, Los Angeles,Calif.

(235 Sunridge St., Playa Del Rey, Calif.) Filed Apr. 22, 1955, Ser. No.503,190

11 Claims. (Cl. 343-712) This invention is directed to transmitting orreceiving antennas for structures and, more particularly, to antennasystems actively utilizing radio frequency currents flowing along theconductive boundaries or borders surrounding discontinuities orelectrically non-conductive spaces in the structures, be they mobile orfixed structures. The invention covered herein differs from that coveredin my co-pending application, Serial No. 487,535, filed February 11,1955, Patent No. 2,923,813, granted February 2, 1960, and entitledAntenna Systems in the structure and circuitry by which the antennasystems and associated receiver circuitry accomplish uniform translationof radio frequency signals independent of the direction of their origin.

Therefore, it is one object of this invention to provide a simpleantenna system utilizing the radio frequency current flowing in ametallic boundary or border about a discontinuity or electricallynon-conductive space in the structure carrying the antenna in such afashion as to derive a pair of signals having a desired space phaserelationship.

It is a further object of this invention to provide an antenna systemfor the transmission or reception of radio frequency energy in which thetransfer of such energy to or from two space-phased portions of theantenna system are utilized in a sequential fashion to providepseudoomnidirectionality.

According to the present invention a plurality of spacephased radiofrequency signals are derived from each of one or more metal-boundedspaces in a conductive structure such as a vehicle. The terms opening,space and discontinuity are used interchangeably herein and are intendedto refer to any region of high electrical impedance at least partiallybounded by an electrically conductive three-dimensional body. Part ofthe extraction of radio frequency energy from the conductive boundarymaterial is derived by a pair of exciter conductors which span thediscontinuity in such a fashion that they are nonparallel or angulated,and, in a special case intersect each other within the discontinuity.Harnesses of the type disclosed in the co-pending application alreadyreferred to may be combined with this angulated exciter wire techniqueto enhance the voltage coupling to adjacent circuitry. Dual channels maybe utilized if desired. Sequential coupling of each pick-up system toadjacent receiver circuitry may be accomplished by a motor drivencondenser rotor having plates of predetermined shape rotatingsequentially into two sets of stator plates of correspondingconfiguration. The combination provides an antenna which issignal-sensitive non-directional in its apparent effect, permitsderivation of two space-phased signals from a single planar opening,exhibits an absolute minimum of electrostatic noise interception and amaximum freedom from fadeouts when used for reception of signals withinstructures normally effecting high degrees of shielding from radiosignals, as for example, tunnels.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention, both as to its organization and mannerpof operation, togetherwith further objects and advantages thereof, may best be understood byreference to the following description, taken in connection with theaccompanying drawings, in which:

FIGURE 1 is a diagrammatic showing of one antenna system according tothis invention.

FIGURE 2 is a sketch of a second form of an antenna system according tothis invention.

FIGURE 3 is a schematic representation of an improved form of theantenna system shown in FIGURE 1.

FIGURE 4 is a diagrammatic representation of an improved form of theantenna system of FIGURE 2.

FIGURE 5 is a schematic representation of a third form of the presentinvention with associated receiver circuitry shown in schematic form.

FIGURE 6 is a schematic showing of a modification of the antenna systemof FIGURE 5.

FIGURE 7 is a modification of the antenna system shown in FIGURE 5.

FIGURE 8 is a modification of the antenna system shown in FIGURE 2.

FIGURE 9 shows a sequential selector for use with the antenna systems ofthis invention.

FIGURE 10 shows the application of the antenna system of FIGURE 1 to aspecific discontinuity or space.

FIGURE 11 is a schematic representation of another embodiment of thepresent invention.

FIGURE 12 is a schematic representation of the use of this invention tohigh frequency applications.

FIGURE 13 is a modification of the embodiment of FIGURE 12.

FIGURE 14 is a further modification of FIGURE 5.

In FIGURE 1, opening discontinuity or space 10 is bounded by theconductive boundary or border of threedimensional body 11. Conductor 12is connected to point 13 on the border of body 11 and the R-F energyappearing at point 13 is applied to output coaxial line 14 at its innerconductor 15. The outer conductor or sheath 16 of coaxial line 14 isgrounded to the conductive border of body 11 at point 17 which is on theopposite side of space 10 but is not directly opposite point 13.Conductor 18 is connected to point 19 on the conductive boundary of body11 and traverses space 10 to connect to inner conductor 20 of coaxialline 21 and the outer sheath 22 of which is connected to the conductiveboundary of body 11 at point 23. Conductors 12 and 18 may be made ofextremely fine wire so as to make them completely inconspicuous.Experiments have shown that it is preferable that the conductiveboundary of body 11 not lie in an absolutely vertical plane. A closedloop of the type which is formed by boundary of body 11 appears to favorthe magnetic field component of the horizontally polarizedelectromagnetic waves and reject other components including undesirablenoise fields, and the more nearly the average plane of the boundary ofbody 11 can be made horizontal the greater the efficiency of the closedloop where multiple signals are derived from one opening.

In FIGURE 2 there is shown an antenna system which is a special case ofthe structure shown in FIGURE 1 in that exciter wires 12 and 18intersect at right angles in opening or space 10 and connect to theconductive boundary of body 11 at points 24 and 25, respectively. Inaddition, outer conductor or sheath 16 of output cable 14 is connectedto the conductive boundary of body 11 at point 26 and outer sheath 22 ofoutput coaxial cable 21 is connected to the conductive boundary of body11 at point 27. As has already been indicated, it is desirable, but notessential, that the conductive boundary of body 11 lie in an averageplane which is not absolutely vertical by reason of the fact that theclosed loop which the conductive boundary of body 11 constitutes hasbeen found to favor horizontally polarized electromagnetic Waves. Ofcourse, the conductive portions of the structure which are horizontaland contiguous to the conductive boundary of body 11 effectively modifythe orientation of the loop formed by the conductive boundary of body 11to give it a horizontal component. The configuration shown in FIGURE 2will provide two signals which are substantially in space phasequadrature.

In some cases it may be desirable to produce voltage multiplication ofthe radio frequency signal which is found across space 10. The voltagemultiplying harness technique shown broadly in the co-pendingapplication previously referred to may be adapted for this purpose. Suchan adaptation is shown in FIGURE 3, in which, exciter wire 18 isconnected to conductor 30 which passes through conductive sheath 31.Conductive sheath 31, in turn, is positioned closely adjacent theconductive boundary of body 11 surrounding space and extendssubstantially half the length of each of the adjacent two intersectingsides of the boundary.

Reference to the earlier filed application will show that in theembodiments shown there the harnesses in most cases extend from a pointalong the lower portion of the conductive boundary of body 11 to a pointsubstantially opposite across space 10. In the embodiment of FIGURE 3 ofthis case the effect of the longer harness is obtained, withouttraversing this total distance, by folding the harness back on itselfand enclosing it in ferrite sheath 34. The connection of exciter wire 18to wire 32 raises the potential at the output end of ferrite sheath 34to a level equivalent to that it would attain if the harness had beencontinued around the window. To reduce confusion conductor 30 is shownas having a single loop through conductive sheath 31 and ferrite sheath34, but to gain voltage multiplication several turns should be utilized.The voltage taken from the harness is applied to the inner conductor 35of output cable 36. Similarly, exciter wire 12 is connected to conductor37 which passes through conductive sheath 38 and returns through ferritesheath 39 either for re-passage through conductive sheath 38 or couplingto external circuits through inner conductor 40 of output cable 41.Exciter wire 12 is also connected to wire 42 which is connected to theremote end of conductive sheath 38 at point 43. Conductive sheaths 31and 38 may be connected to points 44 and 45, respectively, on theconductive boundary of body 11. The amount of voltage multiplicationobtained in either of the harness arrangements may be controlled byvarying the number of times conductor 30 or conductor 37, respectively,passes through conductive sheaths 31 or 38, respectively. An excessivenumber of turns makes tracking of associated antenna tuning circuitsdiflicult, however, so an optimum number of turns must be chosen. Thiscan be determined by experimenting with the particular associated tuningcircuits involved.

The same harness concept may be applied to the embodiment of FIGURE 2and the results are shown in FIGURE 4, in which, exciter wire 18 isconnected to conductor 46 which passes through conductive sheath 47.Conductive sheath 47' lies adjacent the conductive boundary of body 11and, at its extremities, is connected to that boundary as, for example,at points 48 and 49 in FIGURE 4. When conductor 46 emerges from theremote end of conductive sheath 47, it returns to the region of theinput end of conductive sheath 47 and may pass through that sheath aplurality oftimes so as to provide a desired voltage amplification whenit ultimately is connected to inner conductor 400 of output cable 401.In order to isolate conductor 46 on its return le ferrite sheath 402 maybe provided. Exciter wire 18 is also connected to wire 403 which, inturn, is connected to the remote extremity of conductive sheath 47 inthe region, of point 404.

Exciter wire 12 is connected to conductor 405 which passes throughconductive sheath 406 and returns through ferrite sheath 407 either forre-passage through conductive sheath 406 or for connection to innerconductor 408 of output coaxial cable 409. Wire 410 may also beprovided. Conductive sheath 406 is connected to the conductive boundaryof body 11 at points 411 and 412. The configuration of FIGURE 4 providestwo relatively high amplitude radio frequency signals having aspacephase quadrature relationship.

Some improved performance may be obtained by passing the trimmerconnections as well as the tuning inductor connectors through theharnesses. One embodiment of this concept is shown in FIGURE 5 in whichexciter wire 500 is connected to inner conductor 501 of double conductorline 502, the remote end of conductor 501 being coupled to antennatuning inductor 503. The remaining end of exciter wire 500 is connectedto conductive sheath 504 of harness 505 at point 506. Exciter wire 507is connected to point 508 on the conductive boundary of body 11, as isthe outer sheath 509 of double conductor line 502. The remaining end ofexciter wire 507 is connected to conductor 510 which passes throughconductivce sheath 504 of harness 505 and ultimately is connected to thesecond inner conductor 511 of double conductor line 502. The remote endof conductor 511 is coupled to trimmer capacitor 512 and outer sheath504 is connected to the conductive boundary of body 11 at point 513. Bythis technique out-of-phase R-F voltages are applied to the trimmer andtuning inductors in the associated receiving apparatus. Similarly,harness 514 provides a pair of properly phased signals for trimmer 515and tuning inductor 516 of a second antenna input circuit of anassociated receiver, if dual channels are utilized. Harnesses 505 and514 lie adjacent the conductive boundary of body 11. Either conductor500 or 507 may be a hollow rod through which the other passes.

In FIGURE 6 harnesses 600 and 601 are isolated physically andmagnetically from conductive body 11. The magnetic isolation isaccomplished by means of a ferrite sheath covering each of theharnesses. Signals from exciter wires 602 and 603 are utilized to excitethe trimmer circuits of associated receivers whereas exciter wires 604and 605 are utilized to excite harnesses 600 and 601.

In FIGURE 7, no harnesses of the variety shown in FIGURE 6 are utilized.Exciter wire 700 is connected at one end to point 701 on conductiveboundary 11 and at the other end to conductive sheath 702 of outputcoaxial cable 703. A ferrite sheath may be provided on cable 702.Exciter wire 704 is connected between point 705 on body 11 and innerconductor 706 of coaxial output cable 707. The inner conductor 708 ofoutput coaxial cable 703 is connected to body 11 at point 709. The outersheath 7.10 of coaxial output cable 707' is connected to body 11 atpoint 711. The remote end of inner conductor 708 is connected to atrimmer condenser in associated receiving apparatus whereas the remoteend of inner conductor 706 of output coaxial cable 707' is. connectedto. a tuning conductor in associated receiving apparatus. These may beinterchanged. In corresponding fashion a pair of signals is derived frompoints 712 and 713 for application to the trimmer condenserand tuninginductor circuits of associated receiving ap-. paratus in a dual channelsystem. In a dual channel system the signals are translatedindependently through a predetermined number of stages, and thencombined.

If it is desired that; this technique of deriving both trimmer condenserreturn and tuning inductor poten-. tials from the conductive boundary ofbody .11, the structure of FIGURE 8 may be utilized. In FIGURE 8,exciter wire 800 is connected to body 11 at point 801 and its otherextremity is connected to conductor- 802 in conductive sheath 803. Theremote end of conductor 802 may be connected to an input tuning inductorin an associated dual channel receiving system. Exciter wire 804 isconnected to point 805 on body 11 and at the other end to conductor 806which passes through conductive sheath 807 and, subsequently throughconductive sheath 803 for connection to the trimmer circuit andassociated' receiving apparatus. Conductive sheaths 80.7 and 803 areconnected to points 808 and 809, respectively, on the conductiveboundary of body 11.

Exciter wire 810 is connected to point 811 on body 11 and to conductor812 which passes through conductive sheath 813 for ultimate connectionto a trimmer condenser and associated receiving apparatus. An -extensionof conductive sheath 813 is connected to body 11 at point 811. Exciterwire 814 is connected at one end to point 815 on the conductive boundaryof body 11, to which conductive sheath 813 is also connected, and at theother end to conductor 81 6 which, at its remote end, is coupled to atuning inductor and associated receiving apparatus. Thus, both trimmerand tuning inductor radio frequency voltages may be derived which are inspace phase quadrature with a second set of trimmer condenser and tuninginductor R-F voltages. The conductive sheath may be eliminated if properpositioning of wire 812 is eflected.

While frequent mention has been made of a dual channel receiverassociated with the antennas described herein, it may be desirable toutilize these antennas with a single channel receiver by applying asequential technique. A mechanism by which sequential coupling of thespace-phased R-F signals to associated single channel receivingapparatus may be eifected is shown in FIG- URE 9. In that figure thereis provided a rotary capacitor comprising a plurality of sets of vanes900 acting as a first set of stator plates and insulated and angularlydisplaced from a set of stator plate vanes 901, the space betweensuccessive stator plates in stators 900 and 901 being sufiicient forpassage of rotor vanes 903 having the same general sectorial shape asthe stator plates. The rotor plates are insulated in conventionalfashion from the stator plates. R-F signals provided by exciter wire 904are applied to inner conductor 905 of output cable 906 and at the remoteend are applied to stator plates 900. Similarly, R-F voltages appearingon exciter wire 907 are applied to inner conductor 908 of coaxialconnector 909 and at the remote end are applied to stator plates 901;Connection is made to rotor plates 903 through sliding, or otherappropriate contact, 910 and the signals appearing on rotor 903 aretaken through conductor 911 to associated receiving apparatus. Thestator plates 901 are displaced angularly with respect to stator plates900 so as to, in effect, fill the gaps between successive segments orvanes of stator 900. As rotor plates 903 rotate they pass from acondition in which they are closely coupled to stator plates 900 to acondition Where they are closely coupled to condenser plates 901 andthere is a resulting sequential coupling of exciter wires 904 and 907 toexternal receiving apparatus. Exciter wires 904 and 907 provide R-Fsignals having a predetermined space phase relationship so that if space10 is in the body of a moving vehicle and that vehicle changes itsdirection, the relative amount of signal appearing on exciter wires 904and 907 will vary in a compensating fashion, that is, one will rise asthe other falls, and the net signal supplied to the associated radioreceiving apparatus will appear to be substantially constant, thevariations being sufliciently small so that the ordinary AVC system inthe associated receiving apparatus will compensate for the amplitudevariations and the person listening to the receiver will be relativelyunaware of any change in signal strength as the vehicle is turned. Thissame technique may be applied in the case of transmitting apparatusexcept that power would be flowing towards wires 904 and 907. Byincreasing the number of vanes in each set and, hence, by decreasing thesectorial angle covered by each vane, the rate of sequential supply 01:signals to or from adjacent apparatus can bemade so high as to produce asuperaudible beat frequency thus making the amount of objectionableinterference produced by this technique a minimum. The selector may beconnected to a later point in the circuit. It eliminates the need for adual .for the rotary condenser. Electric, pneumatic, hydraulic or othertypes of drive motors may be utilized, or the selector may be driven byan operating member of the car itself. Further, sliding contacts'torotor 903 may be eliminated by providing a separate end stator platewhich is a full circle instead of a segment of a circle, is insulatedfrom the remaining stator plates or vanes and is positioned adjacent anend rotor plate or series of rotor vanes. This same elimination ofsliding contact with the rotor may be efiected by taking each set ofstator vanes and insulating one-half of such vanes from the other halfso as to produce a split stator construction in both sets of vanes. Therotor vanes then constitute the coupling means between the two halves ofeach set of stator vanes and no connection is made to the rotor at all.Of course, a mechanical commutator may be utilized. The eifects ofintercoupling between sets of stator vanes may be minimized by spacingor shielding the sets, or by providing additional sets and applyingsignals from additional points on body 11.

If electronic selection is desired, a pair of gate tubes, one in each ofthe channels from each of the two antennas may be activated alternatelyutilizing successive half cycles of an oscillator operating at asupersonic frequency. The frequency may be chosen to be a subharmonic ofthe desired superheterodyne local oscillator frequency of the associatedreceiver, thus reducing the cost of the over-all circuitry.

In the general case, space 10 need merely be surrounded by theconductive body 11. In the specific case as applied to automobiles, agreat number of discon tinuities or spaces exist from which verysatisfactory radio frequency signals have been derived. Tests have shownthat the further the space is from the automobile engine, the betterwill be the signal-to-noise ratio in the associated receiving apparatus.Innumerable discontinuities or spaces have been used and some have beendescribed in the co-pending application previously referred to.

In FIGURE '10 there is shown a specific discontinuity or space which hasprovided a very satisfactory signal. In FIGURE 10 exciter wire isconnected to point 101 on fender 102. Its other end is connected toinner conductor 103 of cable 104. Exciter wire 105 is connected to point106 on the under side of fender 102. The remaining end of exciter wire105 is connected to inner conductor 107 of cable 108 and exciter wires100 and 105 have an angulated relationship with respect to each otherand may intersect within the discontinuity below fender 102. Outersheaths 109 and 110 are connected to points 111 and 112 on body 113 ofthe vehicle which is mechanically and electrically directly connected totender 102 to form a closed loop therewith. Thus a signal is derivedfrom a cavity below the fender 102. In FIGURE 11 there is shown thestructure for deriving from the region between the body, :gas tank andsplash pan the desired two spaced-phased signals. Harness 115includes'conductive shield 116 which is connected at one extremity topoint 117 on gas tank 118. Conductive sheath 116 also is grounded to thebody of the vehicle at point 119 and at point 120, proceeding in anupwardly direction from the connection at point 117. Bracket 122 extendsdownwardly from splash pan 123 for connection to exciter wire 124, theremote end of which is connected to conductor 125 in ferrite sheath 126.Wire 125 passes through conductive sheath 116 and ferrite sheath 126 aplurality of times depending upon the voltage multiplication desired.Its origin is connected to conductive sheath 116 at point 127 and itsoutput end is connected to inner conductor 128 of output cable 129.

Harness 130 includes conductive sheath 131 which has one end connectedto gas tank 118 in the region of point 117 and is disposed in an L-shapeextending upwardly to connect to the body of the vehicle at point 132and again in the region of tender 133 at point 134. Conductor 135 hasone end connected to conductive sheath 131 in the region of point 134and traverses several loops through ferrite sheath 136 and conductivesheath 131 for ultimate connection to inner conductor 137 of outputcable 138 which has its outer sheath connected to substantially point117 on gas tank 118. Energizing or exciting wire 139 is connectedbetween point 140 on feeder 133 and point 141 on conductor 135. It is tobe noted that the exciter wires are angulated with respect to each otherand that the ferrite sheaths permit the return wires of each of theharnesses 130 and 115 to lie closely adjacent portions of the conductivemembers of the vehicle without undue loading of the return wires. A pairof spacephased radio frequency signals will be derived from thiscombination. Experiment has shown them to be of high intensity andrelatively free of any automobile noises. The ferrite sheaths 126 and136 may be eliminated if harnesses 115 and 130 are not folded back uponthemselves as shown in FIGURE 11.

Discussions thus far have dealt with the applications of the principleof this antenna to broadcast frequency operation. If it is desired toextend the concept to the higher frequencies, for example those utilizedin connection with frequency modulation transmissions, certainmodifications are required. The primary problem which is encountered isthat of properly matching into the impedance of the conductive boundaryof body 11. Techniques for accomplishing the desired matching are shownin FIGURES 12, 13 and 14.

In FIGURE 12 inner conductors 170 and 171 of output cable 172, orextensions of those inner conductors, are fanned outwardly as shown andconnected to points 173 and 174 on body. 11. These points may be chosenempirically to give the desired impedance match between the output cableand the closed loop which the conductive boundary of body 11constitutes.

In FIGURE 13 inner conductors 180 and 181 of cable 182 are spreaddirectly on their emergence from cable 182 and connected to points 183and 184, respectively. The outer conductive sheath 185 of cable 182 isconnected to body 11, as shown.

The connections shown in FIGURES l2 and 13 provide only a single,directional signal. If dual, spacephased signals are required, thecables and connectors may be duplicated and connected to two additionalpredetermined points on body 11 spaced from the initial points.

In FIGURE 14 there is shown a simplified approach to the problem ofderiving trimmer potentials which are out of phase with the tuninginductance signals. Wire 190 which may be an extension of innerconductor 191 of output cable 192 is connected to point 193 along theinner boundary of body 11. The remote end of inner conductor 191 may beconnected to a selector of the type shown in FIGURE 9. Wire 194 isconnected to point 195 on body 11 and its remaining end is connected toinnerconductor 196 in output cable 197. At its remote end innerconductor 196 is connected to the remaining stator plates in a selectorof the type shown in FIG- URE 9. An out-of-phase trimmer excitingconnection is made to point 198 through wire 199 which connects to innerconductor 200' of cable 201. Wires 190 and 194 may be connected to apair of conductors within a single conductive sheath. Wire 199 may bereturned through a brace member of a car window to which has beenapplied a sheath of ferrite material so as to raise its impedance. Otherdiscontinuities or spaces which have been found useful are for example,below the rear window and behind the rear seat, between the rear of thechassis of the automobile and the bumper, and, of course, across thevarious windows, particularly, the rear window of the vehicle and theoverhead, plastic covered window provided in some modern automobiles.

Thus, there has been provided by this invention a numher of embodimentsof antenna systems for use with structures having electricallynon-conductive discontinuities, openings or spaces bounded by conductiveboundaries or borders in which one or more exciter wires are disposed inangular relationship with respect to each other and having at least oneend of each such conductors or wires connected to the conductiveboundary around the discontinuity or space, the remote ends of theexciter wires being coupled either without modification or withtransformation in special harnesses to associated receiving apparatuseither of a dual channel variety or a single channel variety. In thelatter case, a sequential technique is involved and a rotary condensertechnique for accomplishing the selective and sequential excitation ofthe remote receiving apparatus from the dual sources is provided.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects, and, therefore, the aim in theappended claims is to cover all such changes and modifications as fallwithin the true spirit and scope of this invention.

I claim: I

1. An antenna system including a three-dimensional electricallyconductive body having an opening therein; a pair of exciter wires eachhaving one end coupled to said body at spaced points adjacent saidopening, said wires being positioned in angular relationship withrespect to each other and spanning said opening; a pair of harnessespositioned in proximity to said body and adjacent said opening and eachcomprising a conductive sheath coupled at one end to said conductivebody; a ferrite sheath lying adjacent each conductive sheath andconstituting the return leg of the associated harness; a first conductorpassing through the conductive and ferrite sheaths of one of saidharnesses; and a second conductor passing through the conductive andferrite sheaths of the other one of said harnesses, each of saidconductors having one end coupled to one of said exciter wires, itsremaining end being adapted for coupling to associated radio-frequencycircuitry.

2. An antenna system according to claim 1 in which said exciter wiresspacially cross each other within said opening.

3. An antenna system according to claim 1 in which said exciter wiresspacially cross each other at an angle of substantially 4. An antennasystem according to claim 1 in which said opening is a window.

5. An antenna system according to claim 1 in which said conductive bodyis an automobile body and said opening is a window.

6. An antenna system according to claim 1 in which said body is anautomobile body and said opening is at the lower end of a fender cavity.

7. Apparatus as defined in claim 1 in which each of said conductorspasses through its respective conductive and ferrite sheaths a pluralityof times.

8. An antenna system including a three-dimensional electricallyconductive body having an opening therein; first and second exciterwires each having one end directly coupled to said body at spaced firstand second exciter points, respectively, adjacent said opening, saidexciter wires spacially crossing each other within said open ing; andfirst and second leads each having one end coupled directly to said bodyat spaced first and second lead points, respectively, adjacent saidopening, said first and second exciter points and said first and secondlead points being so disposed with respect to each other that voltagesappearing between said first exciter point and said first lead point arespace phase displaced with respect to voltages appearing between saidsecond exciter point and said second lead point, thereby obtainingomnidirectionality, and the remaining ends of said exciter wires andleads being adapted for coupling to external circuits.

9. An antenna system including a three-dimensional electricallyconductive body having an Opening therein; first and second exciterwires each having one end directly coupled to said body at spaced firstand second exciter points, respectively, adjacent said opening, saidexciter wires spacially crossing each other at an angle of substantially90; and first and second leads each having one end coupled directly tosaid body at spaced first and second lead points, respectively, adjacentsaid opening, said first and second exciter points and said first andsecond lead points being so disposed with respect to each other thatvoltages appearing between said first exciter point and said first leadpoint are space phase displaced with respect to voltages appearingbetween said second exciter point and said second lead point, therebyobtaining omnidirectionality, and the remaining ends of said exciterwires and leads being adapted for coupling to external circuits.

10. An antenna system including a three-dimensional electricallyconductive body having an opening therein; first and second exciterwires each having one end directly coupled to said body at spaced firstand second exciter points, respectively, adjacent said opening, saidexciter wires being positioned in angular relationship with respect toeach other and spanning said opening; and first and second leads eachhaving one end coupled directly to said body at spaced first and secondlead points, respectively, adjacent said opening, said first and secondexciter points and said first and second lead points being so disposedwith respect to each other that voltages appearing between said firstexciter point and said first lead point are space phase displaced withrespect to voltage appearing between said second exciter point and saidsecond lead point, thereby obtaining omnidirectionality, and theremaining ends of said exciter wires and leads being adapted forcoupling to external circuits.

11. An antenna system including a three-dimensional electricallyconductive body having a discontinuity therein; first and second exciterconductors each having one end directly coupled to said body at spacedfirst and second exciter points, respectively, adjacent saiddiscontinuity, said exciter conductors being positioned in angularrelationship with respect to each other; and first and second leads eachhaving one end coupled directly to said body at spaced first and secondlead points, respectively, adjacent said discontinuity, said first andsecond exciter points and said first and second lead points being sodisposed with respect to each other that voltages appearing between saidfirst exciter point and said first lead point are space phase displacedwith respect to voltages appearing between said second exciter point andsaid second lead point, thereby obtaining omnidirectionality, and theremaining ends of said exciter conductors and leads being adapted forcoupling to external circuits.

References Cited in the file of this patent UNITED STATES PATENTS2,131,108 Lindenblad Sept. 27, 1938 2,193,500 Usselman Mar. 12, 19402,320,124 Forbes May 24, 1943 2,481,978 Clough Sept. 13, 1949 2,575,471Schweiss et al. Nov. 20, 1951 2,632,851 Lees et a1 Mar. 24, 19532,687,475 Sheldorf Aug. 24, 1954 2,695,406 Byatt Nov. 23, 1954 2,825,061Rowland Feb. 25, 1958 FOREIGN PATENTS 1,012,833 France July 17, 1952

